Guide · Server racks
Rack server vs server rack: what's the difference, and which size do you need?
A rack server is a computer built to mount in a 19-inch rack, measured in rack units (1U, 2U, 4U). A server rack is the steel cabinet or frame that holds rack servers, switches, patch panels, PDUs and a UPS. Pick the rack after you list the equipment: 9U or 12U for a small network, 24U for a few servers, 42U for a full server room.
Rack server vs server rack at a glance
| Rack server | Server rack | |
|---|---|---|
| What it is | A server computer in a flat 19-inch chassis | A cabinet or open frame with 19-inch mounting rails |
| Measured in | Height in U: 1U, 2U, 4U (1U = 44.45 mm) | Total U of mounting space: 9U, 12U, 24U, 42U |
| Depth that matters | Chassis depth, often 700–800 mm or more | Cabinet depth: 450–600 mm wall-mount, 800–1000 mm floor-standing |
| Examples | Dell PowerEdge, Lenovo ThinkSystem and ASUS rack servers | Wall-mount cabinet, 42U floor-standing cabinet, open-frame rack |
| You need it when | You run applications, files or virtual machines on site | You need to hold, secure and power servers and network gear |
What is a rack server?
A rack server is a server computer in a flat, wide chassis that bolts onto the two front rails of a 19-inch rack. Its height is given in rack units: a 1U server is 44.45 mm tall, a 2U server 88.9 mm. Rack servers slide out on rails for service and share the rack's power, cooling and cabling with the network equipment around them. Tower servers, by contrast, stand on the floor or a desk and don't need a rack.
We quote rack servers from Lenovo (as a Lenovo 360 Authorized Partner), Dell and ASUS, with Seagate drives for storage builds.
What is a server rack?
A server rack is the enclosure. Most are steel cabinets with a lockable front door, side panels and adjustable 19-inch mounting rails, either wall-mounted for small networks or floor-standing for servers. Open-frame racks drop the doors and panels for secure rooms where access is already controlled. The rack also carries the rack accessories: PDUs, shelves, cable managers, fans and blanking panels.
Which size do you need: 9U, 12U, 24U or 42U?
The U number is the usable mounting height. The cabinet itself is taller because of the frame, roof and base. As a rule of thumb, add up the U of every item you plan to mount, add 25–30% spare, and check the deepest item against the cabinet depth.
| Rack size | Mounting space | Typical use | From XG Labs |
|---|---|---|---|
| 9U | about 400 mm | Wall-mount. A router, one or two switches, a patch panel and a small NAS in an office or shop. | Quoted on request; availability confirmed on the quotation |
| 12U | about 533 mm | Wall-mount. Office network: switches, patch panels, firewall, cable managers and a small rack UPS. | Listed: 12U wall-mount, 600 × 450 × 640 mm |
| 24U | about 1067 mm | Floor-standing, half height. One to three rack servers plus a UPS, or a branch comms room that will grow. | Quoted on request (a 22U 600 × 800 mm floor cabinet is also available on request) |
| 42U | about 1867 mm | Floor-standing, full height. Server rooms with several servers, storage, UPS and rear PDUs. | Listed: 600 × 1000 mm (servers) and 600 × 800 mm (network), 2055 mm tall |
Full dimensions for each listed cabinet are on the 42U server rack page and in the server rack size guide.
A worked example
An office with two 2U rack servers (4U), a 1U firewall, two 1U switches, two 1U patch panels, two 1U cable managers and a 2U rack UPS needs 13U today. With 30% spare that is about 17U. The servers rule out a shallow wall cabinet, so the sensible choices are a 24U floor cabinet or, if the room allows, a 42U 600 × 1000 mm rack that leaves space for storage and a second UPS later.
Depth, power and airflow
- Depth: measure the deepest server and add 150–200 mm for cables and PDUs. That is why 1000 mm is the usual depth for server racks.
- Power: plan a rack PDU and a UPS sized to the load. See rack PDUs and UPS.
- Airflow: perforated doors, blanking panels and, where needed, roof fans keep front-to-back airflow working.
On-premise racks in a cloud or hybrid setup
Moving workloads to Google Cloud, Microsoft Azure or AWS usually shrinks the rack rather than removing it. The firewall, switches, Wi-Fi controller, backup storage and any servers that must stay local still need a home. If you are planning a hybrid setup, list what stays on site and we will size the rack, power and network hardware for it.
Rack recommendation
Send your equipment list, get a rack size and a price.
List the servers and network gear you plan to mount, even roughly. We recommend the rack size and depth, add the PDU, shelves and UPS you need, and quote it in writing. Every order is quoted in writing.
Prefer to talk? WhatsApp 011-4574 4754 · Call · sales@xglabs.com.my
Frequently asked questions
Is a rack server the same as a server rack?
No. A rack server is the computer. A server rack is the cabinet or frame it is mounted in. One server rack usually holds several rack servers plus switches, patch panels, PDUs and a UPS.
How many U is a rack server?
Most rack servers are 1U or 2U high. Storage-heavy or GPU servers are often 4U. 1U is 44.45 mm (1.75 inches).
Which rack size do I need for one or two servers?
Add up the U of the servers, switches, firewall, patch panels, cable managers and UPS, then add 25–30% for growth. Two 2U servers with a typical network and a 2U UPS come to roughly 13U, so plan on a 24U floor cabinet, or a 42U if the room allows. Servers need floor-standing depth (1000 mm is the usual choice), not a shallow wall-mount cabinet.
Can I put a server in a 12U wall-mount rack?
Usually not. Our 12U wall-mount cabinet is 450 mm deep, which suits switches and patch panels. Most rack servers are deeper than that and too heavy for a wall cabinet. Use a floor-standing rack for servers.
What is the difference between 600 × 800 and 600 × 1000 mm?
Both are common footprints for 42U floor-standing racks. 600 × 1000 mm leaves room behind full-depth servers for power cables and PDUs, so it is the usual choice for servers. 600 × 800 mm suits network-only cabinets.
Do you supply rack servers as well as racks?
Yes. Rack servers from Lenovo, Dell and ASUS can be quoted with the rack, PDU and UPS, so the whole bill of materials is on one quotation.
Free server room site check
Book a free server room site check.
We check the room, power and airflow, then recommend the rack and accessories. On site or by video call. No charge, no obligation.